This invention relates to electrical anti-theft devices useful in preventing thefts of automotive vehicles.
Many types of anti-theft systems have been proposed to combat the continuing problem of vehicle theft. One approach is to provide sensors which activate a siren whenever an unauthorized entry is made into the vehicle. Another approach is to provide a hidden switch which disconnects the ignition system. Yet another approach is to provide a removable part without which the vehicle cannot be started. The U.S. Pat. No. 3,492,494 (Clark, et al.) proposes the use of an electronic switch that includes a removable resistor which can be located on an ignition key and without which the ignition key will not energize the starter motor of the vehicle.
All proposed approaches suffer from inherent disadvantages which limit the usefulness of systems constructed in accordance with these approaches. For example, a system which relies on a siren to deter vehicle theft is not entirely satisfactory because the sound of the siren often does not attract immediate attention in busy cities. It is also difficult to determine which vehicle is being broken into. Similarly, hidden switches can be discovered or by-passed by a thief. Likewise, the removal of a part essential to the operation of a vehicle involves several disadvantages. First, it is cumbersome and inconvenient to remove various parts. Second, there is an inherent problem connected with situations where more than one person drives the vehicle, each person having his own set of keys. The person intending to drive the vehicle must obtain the removable part from the one who last drove it. The approach proposed in the Clark, et al. patent involves a complicated electronic circuit and is therefore relatively expensive.
The present invention provides an automotive anti-theft system which overcomes disadvantages inherent in the prior art systems. Thus, one object of the present invention is to provide an anti-theft system which cannot be either by-passed or disconnected by cutting wires.
Another object of the invention is to provide an anti-theft system which does not inconvenience the operator or operators of the vehicles in any manner whatsoever.
A further object of the invention is to provide an anti-theft system which is compact, and simple and inexpensive to manufacture.
A still further object of the invention is to provide an anti-theft system, a major portion of which can be mass produced in form of a low cost resistor network.
Still another object of the invention is to provide an anti-theft system which can be simply and inexpensively installed in existing or new vehicles.
Other objects of the invention will become apparent to those skilled in the art upon studying this disclosure.